The state of the art includes numerous documents relating to battery mounting devices.
International Patent Application No. WO 01/77760 A1, published on 18, Oct. 2001 discloses a device for mounting a button type battery in an electronic watchcase. This device includes, in particular, a substantially cylindrical housing, moulded from plastic material and opening onto the back face of the watch. The housing includes, on its periphery, tongues extending from the bottom towards the opening and preferably moulded in one piece with the housing. Each tongue has a bent portion, in its end region, provided to form a support zone on the face of the battery oriented to the side of the opening, when the battery is mounted in the housing. Mounting is achieved by elastically deforming the tongues.
It should be noted that this solution provides that the bent portion of one tongue widens from one edge of the tongue towards the other so as to have a support zone with a sufficiently large surface area to guarantee that the battery is efficiently held axially in the housing.
However, this particular structure has one drawback in that in order to introduce a battery into the housing, the latter has to be inserted slantwise through the aperture of the housing. Thus, this insertion is difficult to implement in an automated assembly line.
Further, the structure described in the aforecited International Patent Application has another drawback linked to a risk of the battery being held defectively in the event of a shock. If the shock is sufficiently violent, the battery, which has a relatively large mass compared to the constituent elements of the watch, can be projected in a direction such that it can deform the elastic tongues and be removed from the housing. In such case, the first consequence of the inadvertent movement of the battery is a risk of interrupting the supply of electric power to the watch.
One solution to this problem is provided, in the International Application, to improve the hold of the battery in its housing. For this purpose, one particular embodiment provides snugs placed on the top of the bent portion of the tongues, these snugs cooperating with the cover or bottom to deform the tongues substantially in the direction of the battery. Thus, the latter is better held in its housing in the event of a shock.
However, a brutal movement of the battery can cause additional problems, in particular when the cover closing the housing or, in the case of the aforecited document, the back cover of the watch, is not securely fixed to the case, for example screwed on or held by screws. By releasing itself from the tongues, the battery can be projected against the cover of the housing and damage the fixing of the latter to the watchcase. In the case of a water-resistant watch, this can lead to a defect in the water resistance of the watch. Moreover, depending on the force of the shock, the cover can be completely released from its housing and get lost. The embodiment providing snugs to prevent deformation of the tongues does not properly overcome this problem since a significant force exerted on the tongues by the battery is directly transmitted to the cover towards the outside of the watchcase. The cover can thus also be released from the housing in this case.